This invention relates to a method for sealing the joints between adjacent panels of a dryer, such as a veneer dryer, against the escape of hot gases from within the dryer.
Dryers, such as those used to dry wood veneers, generally comprise large chambers formed of multiple panels. Veneer is passed through the dryer and is heated to drive moisture from the wood, the temperature within a veneer dryer being in the neighborhood of 350.degree. F. At this temperature, and at the elevated pressures found within a dryer, the moisture driven from the wood remains substantially in a vapor state and has a tendency to leak through spaces between adjoining panels in the dryer. Such moisture, which includes water vapor, hydrocarbons and acidic materials, experiences a drastic lowering of temperature as it leaks from the interior of the dryer toward the outside of the panels causing it to condense on the panels in the regions of the leaks. The condensed moisture corrodes or deteriorates the panels, producing larger gaps between the panels and allowing greater leakage. This increases fugitive emissions from the dryers which are objectionable and often are in violation of environmental control standards. Moreover, the performance and energy efficiency of the dryer are decreased by the leakage, and thus the dryer's cost of operation is increased.
The problem of attempting to seal such dryers against leakage is primarily in making the seals tight enough that they can effectively resist the leakage of the hot, pressurized gas from within the dryer to the ambient low temperature and low pressure areas outside the dryer. This problem is aggravated by the fact that each dryer contains not only a large number of joints between panels, but also joints of many different configurations between different types of panels, such as between roof panels and side panels, between side panels and door panels, and between door panels and floor panels. Moreover there are also joints between panels and members which penetrate the panels, such as pipes and air ducts. Some dryers also have joints of the expansion type, wherein two panels are movable toward and away from each other in response to temperature variations.
Accordingly the principal object of the present invention is to provide a method for sealing dryers, especially veneer dryers, which overcomes the problems set forth above.
More specifically, an object of the present invention is to provide a method for sealing the joints between adjacent panels of a dryer against leakage of hot, pressurized gases from within the dryer through such joints.
A still more specific object of the present invention is to provide a method for sealing such joints which can be applied to existing, fully-assembled dryers by structural modification of such dryers while they remain in the assembled state, and which is well adapted for sealing the various different types of joints described above.
A principal feature of the invention is to employ a heat-resistant, gas-impermeable closed cell foam as a sealing material and to utilize the heat generated by operation of the dryer to expand the closed cell foam after installation and curing thereof to tighten the seals and thereby complete the sealing of the dryer.
The foregoing and other objectives, features and advantages of the present invention will be more readily understood upon consideration of the following detailed description of the invention taken in conjunction with the accompanying drawings.